I've been reviewing various drywall videos and documentation but I haven't found clear details on what kind of thickness the joint compound should be. Is there a definitive answer for this? Or does it vary? Even videos with "pre-mixed" compounds still mention adding additional water.

3 Answers
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I found it took me a couple hundred hours of applying mud to get to the point where I knew exactly how I wanted it to look. I learned just fine by starting with the pre-mixed straight out of the bucket and slapping it on the wall. You'll quickly notice the difference in application ("spreadability") when it starts to dry in your mud pan a little bit. Then you add water - too much the first time of course - and the mud will fall off your knife before you can get it to the wall.

Just keep in mind, it might take more than two or three coats, but if you can spread it on the wall you can't really screw up the consistency. If it's too dry, it will crumble as you press it with the knife, if it's too wet it will fall off your knife (and the wall).

Thanks Steve. It's a relief to know that I won't "break" things if I don't get the mud consistency exactly right the first time.
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Mike BOct 25 '10 at 16:06

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Then you add water - too much the first time of course Kind of like learning to mix concrete. There's a fine line between holds a groove when you draw your finger through it and liquid mess. Seems like that last extra pint in the wheelbarrow does the damage.
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Fiasco LabsFeb 2 '14 at 20:09

I've always heard it should be the consistency of cake frosting, but I find that to be still a little subjective. It should be smooth and creamy, thin enough to spread easily without falling off your drywall knife.

In practice, I just mix it up until I think it looks close, then start using it, and if it's not going on well I'll adjust the mixture. After applying a couple of pans full you'll definitely be able to tell when it's too thick or thin.

It's going to depend a bit on what you are doing. If you are filling in low spots or holes where you'll be applying a thick coat, use a nice stiff mixture (stiffer than out-of-the-bucket pre-mix).

For a normal first or second coat, I'll usually use pre-mix right out of the bucket without thinning it down at all. Then for the finish coats I'll ad a bit of water to make it spread more easily and get a smoother finish.